With the development of data storage techniques, various data storage devices now provide users with higher data storage capacity, and also their speed of accessing data has been increased greatly. So far various RAID-based data storage systems have been developed to increase data reliability. When one or more disks in a storage system fail, data in failing disks can be recovered from data in other disks operating normally.
The storage system may be accessed via storage control nodes. In a typical active-active (also referred to as dual active) type of storage system, two storage node controls work jointly to process data access operations on the storage system and further provide higher availability and better performance. Each storage control node has its own memory (e.g. cache), and memories in two storage controllers operate in a mirroring mode.
Besides the increase of data storage capacity, users also impose greater demands on response time of storage systems. At this point, it becomes a focus of research regarding how to improve data response efficiency while ensuring data consistency in storage systems.